The Dutch actress passed away in her sleep in Holland after a long battle with throat, lung, and esophageal cancer. She was 60.
Jaeckin, who directed Kristel in the erotic 1974 film, remained close to the star after wrapping the project, and now he has spoken out about his loss, telling BBC News, "I'm sad because she was part of my life... She was like a little sister."
He last spoke to her in February (12).
Kristel began her career as a model at the age of 17 before landing her breakthrough role as a promiscuous housewife in the widely-successful soft core movie and its subsequent sequels.
She later built upon her image as a sex icon in Lady Chatterley's Lover, Mata Hari, and American comedy Private Lessons. She additionally played bit parts in TV shows My Riviera and The Swing Girls, director Cyrus Frisch's film debut Forgive Me, and foreign drama Two Sunny Days.
In 2006 she received a jury award at the Tribeca Film Festival in New York for directing the animated movie Topor and Me.
She is to be buried in a private funeral.